Honestly, tile is hard on any reptiles joints, I use children’s play for my dragons, with correct husbandry it should be an issue but with Uros I’m not sure, I know they’re desert animals with similar husbandry as Dragons so I imagine it would be no issue with children’s play sand
I dont have a uro, but have been setting a tank for one for a while now. I used playground sand for mine. I know a lot of people use millet seed though, as it can be a part of their diet and it eliminates impaction risks if ingested. But if you want something more natural, any sand should be good. As long as it is a soft sand with no sharp edges